Filling the Void
by AimaZero
Summary: When Ulquiorra started disappearing he knew something was wrong, he just couldn't predict what would actually happen.
1. Prologue: A Heart

Buildings were being destroyed one after another.

Two devils were fighting outside of Las Noches and alarming everyone that was inside of it.

One of the devils was a pale monster with horns and a hole where its heart should be, it was one of the most aggressive creatures that existed.

The other one was a devil in every sense of the word, pale skin, black wings in the shape of a bat, his green eyes with slit pupils were surrounded by black despair in a blank expression that showed only that even though his opponent was much stronger than him.

He did not care.

The two should be considered devils.

Monsters or beasts.

But only one had in mind the destruction of his opponent.

The white devil with the long orange hair was a juggernaut that could not be stopped by anything the black haired devil threw at him.

In a moment the battle stopped. The two of them looking at each other, wondering what would the other will do.

"Don't move, I don't want to throw this near me if I can help it."

Said the black devil while concentrating power in a lance.

Then he threw it, and all hell broke loose.

An explosion that ran for miles illuminating everything that could be seen, was not in the minds of the two devils fighting.

And they threw themselves at each other with everything the had.

Instinct guided the pale beast with horns, while the black devil thought of something other than the battle.

'What is a heart?'

'I'm not trying to win because I want to, but because I have to!'

'Are you scared?'

In effect, the beast he was fighting was the remnants of one Kurosaki Ichigo that should be dead.

It was something unexplainable, it should not be possible.

He had plans for after dealing with Kurosaki Ichigo, but it seems he lost the opportunity to execute them.

He planned to kill Aizen at a moment of surprise of his Resurreccion Segunda Etapa, then get the Hogyouku to learn what is a heart.

While having these thoughts he made a slip.

It was only a tiny fraction of a second.

But by the time he realized, it was already too late.

"So I lost, huh?"

By the time he said that the monster stomped on his head pointing his horns at him, already forming a Cero.

"I see, ruthless, just like a hollow."

He didn't mind dying, it was actually something he looked forward to.

'If I die, will I see a heart?'

The everything exploded in red, his last vision was that of the woman that isn't afraid of him.

He put the last defense just as half his body was already gone, feigning unconsciousness.

Not in a million years would he go out without taking his enemy with him, he just needed one chance.

'NOW!'

In the blink of an eye, he was pointing his lance to the neck of the beast intent on cutting its head off, but in the last second, it moved out of the way.

Still, his mask broke, and Kurosaki could have been dead if not for his curiosity.

As if nothing had happened, he woke up and saw his friends.

Then he recognized his enemy.

"Ul-Ulquiorra"

"Who did that to you?" Then he looked at his friend, "Uryuu, are you okay? who did that to you?"

Ulquiorra almost felt pity for him, but this farce had to end, his friends didn't want to tell him what happened, well in that case...

"Have you forgotten? you were the one that did this to me and the one who wounded your friends."

It was incredible that after all Ulquiorra did, it was hurting his friends that gave him despair.

Something was wrong with him, Ulquiorra could feel it, he should have reverted to a form that used up less reishi, but he was still in his Resurreccion.

"I can't accept this!"

Oh? What could be done about that?.

"Ulquiorra!, fight me!"

That was a stupid resolution, even in this wrong state he was in Ulquiorra was certain that one hit was enough to kill him.

"That thing you fought, it wasn't me!"

So that's why, is this about the heart, maybe he could learn about it in the next battle.

"Alright"

It shouldn't be possible but he felt something spark inside him as if the truth had been revealed to him but he couldn't grasp it.

He prepared himself to fight, but then a crack was heard and his wings started becoming dust and following to his body in increasing speed.

"I see, so this is the end, huh?."

He looked at the woman he held captive extending his hand towards her, formulating the last question in his mind at the moment.

"Do you fear me?" he said, retracting with little strength his hand, he felt too fragile to move.

"I'm not afraid of you" replied the woman, not realizing that the spark he felt would become a fire that he simply couldn't ignore anymore.

"I see" the woman reached out as if to touch his hand, but it started becoming dust before she could reach him.

"What I feel in my hand, it's a heart.."

These were his last words in this world.

* * *

The blinding light was the first thing he saw, and a burning pain he couldn't react to for it was nothing against the pure confusion he felt.

Why did he remember everything he lived as a hollow?.

Being reborn meant that his memory would start over from nothing.

And in the first place that creature Kurosaki had become destroyed his soul.

He had no doubts about it, he was supposed to have been obliterated.

Yet here he was being born again.

"Why isn't he crying? I thought babies were supposed to cry when born.?"

He couldn't make out who said that everything was blurred.

"Maybe something is wrong with him, I'll have to put him under observation for a while"

Ulquiorra was then put in something soft, and in a moment he heard something strange, it was like Grimmjow in his Resurreccion.

"GRRROOOARR"

And with a roar as his lullaby, the unnamed baby that was Ulquiorra fell asleep.


	2. Chapter 1

_**Bleach and Naruto belongs to Tite Kubo and Masashi Kishimoto**_

 _ **And none of the characters or places belong to me.**_

 _ **Author note: to be completely honest I haven't thought of the future of the story but I will have to mention some retcons I will not explain in the story itself, for example, .1-Black Zetsu: I will introduce him as a character but he will not be the mastermind of everything that has ever happened, that's just dumb, history was made from choices, not from a mama's boy.2-Naruto/Naruko: even though he/she is not listed as a character in this story, he/she will play an important role, I just haven't decided yet if it will be Naruto or Naruko that will appear in the story. though I'm thinking of using she.3-Sakura: nothing against her but I'm thinking of not making her appear, a different chain of events by making Zetsu retcon, some things have to change, and I don't think she has a lot to offer as a character. now, thanks for reading, hope you enjoy.**_

 _ **Chapter 1**_

 _ **Something new**_

It was a new day in Konohagakure, the sun was just beginning to rise, and no ninja of the village had the chance of sleep, granted they were accustomed to keep on going without sleep, it was a considerable effort to stay focused after last night's proceedings.

The Kyuubi had reappeared, and it destroyed half of the village and killed many ninjas and civilians, this fact weighed on the mind of everyone, giving a gloomy atmosphere to the place.

Many ninjas were helping to find people or the corpses that were found in most cases.

People squashed like bugs, parents protecting children that died of asphyxia, unable to breathe.

One ninja in such a job was none other than Uchiha Shisui.

even if his orders were to keep a low profile, when had he listened to his superior's orders over his own heart?

Maybe he was one of the ninjas that saved most people that day.

Officially at least.

His Sharingan was too sharp to ignore the blank masks that happened unto some of the surviving children.

The only place now left to look for, and the place where most people were for looking survivors in, was the hospital.

Shisui didn't think he would find anyone alive in there, more the great number of people looking for their family, but something told him that he should look for someone, anyone.

He knew that his mind was playing tricks on him, the Kyuubi was a terrifying creature, but the fourth Hokage killed it at last.

In the midst of thinking, and with his Sharingan activated to look for small details, aside from training, of course, he was pretty sure 3 tomoe wasn't the end of it, he saw a flicker of movement down in at least 3 floors worth of rubble.

He immediately sprung to action.

"Hey!, I found someone!"

That shout pierced through the gloomy faces of many that were looking around, hope igniting in their hearts that they would find someone they knew.

And after some minutes of scavenging around, careful not to make the rubble cave-in itself, he saw it.

Big green eyes with slit pupils opening and tiny pale hands going to his face accompanied in a yawn was a baby, that must have just been born, for it was really, really small.

With utmost carefulness he ripped someone else's shirt, accompanied with a shout of indignation, and proceeded to wrap the baby in the cloth bringing him close to give him body heat, it was a wonder how the baby had survived the whole night in the place.

It could only be a miracle the baby was alive, and he now had to think of where to go for someone to check if he was alright.

With a shudder, he decided to go to his clan to request some help dealing with the baby.

'How the hell am I going to explain why I took a baby during Anbu patrolling?'

He had rescued some children, but a baby was new grounds for him, and he already was speeding to the clan grounds so he couldn't dump the responsibility to someone else.

* * *

Once he entered the land given to the Uchiha, he went to give a report to Fugaku, if he was already there, why not just kill 2 birds with one stone.

Give his report about the dealings in Anbu, while having the excuse of leaving a baby in the care of someone with experience, it was good to be anonymous in Anbu.

So he entered to the Clan Leader's house and noticed a 7-year-old kid with a baby in his arms.

He stared, a plan that started as a joke gaining more ground in his tired mind.

"How the times have changed, in my times a kid played around with his friends instead of recklessly having sons at such a young age"

He said closing one eye, and hiding the cloth with a baby behind him as if hiding a present.

The kid meanwhile got flustered by the ridiculousness of the man's statement and heatedly got up with his little brother carefully held in his arms.

"Wha- I'm not Sasuke's father, I'm just taking care of him until mom comes back!"

"Oh? so you're his babysitter then?"

The kid the carefully nodding, a feeling in his gut telling him he should've stood silent.

"I guess so"

Said the kid confused by the question.

Then as if it was the most normal thing in the world, the man took something small from his back and gave it to him, the absurdity of what he thought the 'gift' was numbing him enough to hold Sasuke in one arm and receiving the definitely 'not a baby' from the man that he could never predict would become one day his best friend.

"Ok, then, I leave him to you, take care of him okay? bye, babysitter-chan~"

and as the man disappeared in a Shunshin, he resigned himself to taking care of the new baby, at the very least.

"Sasuke, say hi to our new friend"

Sasuke now had some baby company to distract himself.

'this must be the weirdest series of events I will bear witness during my life, I swear if something more ridiculous were to pass he would go on testing his skills in every Uchiha he saw, it was the blood, he knew, every Uchiha had a weird series of events surrounding him.'

* * *

Ulquiorra watched in amazement the view in front of him.

At first, he was confused as to why everything was so dark, he even thought he died again.

Then that man came and picked him up, enveloped him in other guy's shirt, and it was puzzling him to no end the marvels of feeling.

For the first time since he could remember he felt something, he was freezing, and now he felt something unexplainable by being held by the arms of the man, it was hard to explain but it felt warm, his insides were telling him he was safe.

The man then started running at a speed he was certain no human should be able to, but then again, his only interaction with humans so far were children, the woman, and the boy he tried to break at the time.

And thinking back on it, breaking that man ended up backfiring.

In the end, the one broken, in half, was him.

now that he was able to see, he saw with amazement a 'natural' blue sky, then there was the green in his surroundings, it was so colorful that he wanted to just explore every bit of it.

But he couldn't, he didn't have the strength to pull himself free of the man's vice-like (gentle) grip.

It definitively wasn't because he liked feeling the warmth...

For a short moment he fell asleep for a little time, it was scary how even thinking was a process that demanded so much energy he had to sleep for a while.

Then in a moment, everything changed.

The warmth disappeared suddenly, and it felt as if everything was upside down.

He heard some noises, but he couldn't understand anything out of it, there was something that he could identify, it vexed him greatly that he couldn't understand because he needed to know.

If Aizen could ever read his mind, he would have found an even greater motivation to keep his loyalty, now that he thought about it, who had won?

Kurosaki Ichigo with his unbreakable convictions or Aizen with his search for perfection?

He was pretty sure Ichigo had won, if not for he was sure the Shinigami took a new power out of his ass.

He wasn't bitter with his defeat, in fact, it gave him this opportunity to comprehend, but killing a man 3 times for the same man to kill him in the end.

Indeed Aizen had lost, he was sure of it, if Ichigo could bring feelings to a personification of Void, Aizen was child's play, with the Hougyoku in the middle of th-

Everything changed again.

He was suddenly in smaller arms, that somehow brought him more warmth than the man.

He looked up to the new face, a kid.

The kid said something to the other baby, that he just now noticed.

And in the middle of the day, and not for the last time with a curious mind as the cause of it, Ulquiorra was out of energy fast asleep.

The new year in his life was a plethora of new experiences, drinking milk for the first time from the mother of the other baby to keep his body working.

Basically 'eating', was a concept completely new to him.

As a hollow, he was different, he killed not to eat but to survive not being eaten in the sands of Hueco Mundo.

Born without a mouth, trying to understand without a heart, he never ate anyone, the state he was born in, was the state Aizen found him in, a white hollow contrasting the dark world of the eternal night he was born in.

Not this time.

This time he had a heart, and he would give everything to nurture this heart that puzzled him so much, that was his.

and with him being given to the orphanage, 3 years passed in the blink of an eye.

* * *

 _ **And that's it for now, I'm starting this fic, as a means to add to the small list of fics with Ulquiorra as a proper character, I hope I'm doing this fine, I want to introduce to Ulquiorra the concept of heart and how he will react to it alongside the storm of events that is Naruto.**_


	3. Chapter 2

**Hello there, after 2 full days of pondering about it, I chose to make 'Naruko' for the Kyuubi's container this time around, if I decide to make another story, I will use 'Naruto'.**

 _ **Disclaimer: Naruto is property of Masashi Kishimoto and Bleach is from Tite Kubo and I'm in no way, shape or form owner of any of the franchises if I was Ulquiorra would have for sure been the final enemy as a rival to Ichigo. Well, Enjoy.**_

 ** _Chapter 2_**

* * *

 ** _Start of a legend._**

It was morning in the third year of his life, and Ulquiorra was coming to a realization in regards to his powers.

There was not Reishi in this world.

He couldn't use any of his abilities, though his Hierro seemed to retain in some form along with his regeneration which was completely unaffected by being reborn.

Things that he should NOT have, as being reborn meant being a blank slate to look forward to.

How was he certain his regeneration was untouched?

Well, that was quite simple.

By having fallen from a tree directly into a sword lodged in there, which ripped his arm off.

The reason a three-year-old boy was escalating a tree definitely didn't have anything to do with his curiosity over the pair of birds that were in a branch feeding their chicks in their nest.

The thing was, it's pretty problematic having suddenly a black arm.

And it's predecessor by a sword near the woods of Konoha, it will be food for the fauna at least.

That was another thing.

He liked animals, or at least the people in the orphanage said to him it was 'like'.

he just asked why he felt his chest tighten up when he saw the carcasses of animals in the shopping districts, and then they showed him a puppy, and he said his chest felt warm, then they explained what that feeling was.

He liked the orphanage, but not the people in there.

They rejected him, always he was treated as if he wasn't there.

The children treated him like a freak, and he told them that he really was a freak by the definition of it.

In his mind, they were justified, even as a hollow the other ones were cautious of him.

Then the grown-ups one day started treating him like he was a monster.

In the start, they used to give him things for free but one day he just jumped to the roof of a house in the night and they said he was possessed by some sort of fox or something weird like that.

It just didn't make sense.

They liked him one day and the next they rejected him.

Humans didn't make sense, not even himself.

"Ul-chan~ how are you today?"

"I'm doing fine, Shisui"

There he was, the insufferable bastard which attitude he could maybe compare to an amicable Gin Ichimaru.

A stupid, pathetic, clown that for some reason gave him this warm feeling.

"Hey, little one, why are you hiding your left arm? and what's with the blood? and that swor- Oh my god, Ulquiorra, are you ok?!"

He felt conflicted when he saw the concern in the man's eyes, so he showed him his now increasingly pale arm while pointing at the limp arm on the floor with it.

"Don't worry, Shisui, it just grows again, there is no problem"

Then as if he said something he shouldn't have, a silence so thick you could walk on it surrounded the area.

"What?"

* * *

This kid was really weird.

Shisui thought he could react to any situation that arises suddenly with a calm mind, and he probably could if his opponent suddenly regenerated missing parts.

Orochimaru was an example of such type of ninja if the information Anbu had on him was to be trusted.

But seeing the little kid he always visited around the orphanage act as if cutting his arm off was a normal, everyday thing, really shook his core.

He instead chose to forget there was an arm thrown on the floor and decided to ask little Ulquiorra, god that was a weird name, what he came here for.

"Hey, Ulquiorra, do you want to be a ninja"

"What is a ninja?"

Really, this kid was curious to the bone, yet never considered the question of why there were people in the village that could jump around everywhere armed with kunais and blades?.

"Ninja are people that train themselves to be stealthy, good fighters, that protect the village and the people that live there."

"I see, are they strong?"

"It depends, but generally they are"

"Then, yes, I want to be a ninja"

"Okay, that's marvelous, you would have to go regardless as an orphan so I came to ask if you really wanted."

That's a relief, honestly, if he didn't want to be one, he would have to get him out of the village, a not so wise move now with the tensions high between the Uchiha clan and the village.

"See ya later, Ulquiorra, don't do dangerous things like that without supervision, you could die you know?, and if that happened your big brother Shisui would be really sad."

* * *

'I would be sad if you died too'

Were the words Ulquiorra wanted to say.

But now, he would have to take the sword in the tree with him, the person who left it there was to blame, and he needed something he was familiar with, when he is older he'll need one, and this one's sharp enough to cut through his fraction of Hierro left.

And for some reason, no one came to this forest, so he liked to spend time here to think about things.

And so the day ended with no more surprises.

* * *

He never noticed the snakes watching him intently, even as he got away.

* * *

Some days later, it was finally the day.

Shisui was walking little Ulquiorra to the first day in the academy for orphans.

Clan kids were taught in their clans until a certain age, it varied between 7 or 8 years, this was due to orphans needing more time to learn because no one would teach them outside of school.

"Shisui, you don't need to walk me to the academy, you aren't my dad so there's no need"

Really this kid.

"You know, if I was married I would have adopted you, even now you're like a little brother to me, the same as Itachi-chan"

He knows he cares about him, he always tells him, but he doesn't know how to accept being taken care of by other people.

"And so, it's my duty to see which girls you pick the interest of, heh, if not for your eyes I would say you're an Uchiha, so you'll be really popular with ladies."

"But if you're an Uchiha, why don't you have a girlfriend, Shisui?"

"Gah!, that's... forget it, we're not talking about me here"

Then he saw his face and the innocent curiosity in his face, and with resignation proceeded.

"The majority of Uchiha have good looks, but some of us are cursed with a plain face, injustice I say, so that's why I'm not popular"

"But why are looks a thing that matters? shouldn't power be the thing that's attractive to females?"

This kid doesn't know anything about relationships!

And like that, they finally arrived at the academy, with Shisui parting disappointedly from Ulquiorra.

* * *

He made it to the classroom, which was already filled to some degree, and was promptly pushed to the side by a yellow blur.

"Ouch!"

"Hmph"

And like that green eyes met blue for the first time.

* * *

 _ **That's it for now, in the start I was going to add until the Uchiha massacre, but realized that it was 4 years in the future and I needed to show some more things before that, so there's that, and by the way, thanks for everyone reading this, I hope I'm improving and this gets interesting, i will publish chapters when they're ready and I write more when I can't sleep so wish me bad sleep. Just kidding, but I should explain that I'm not an English native speaker, even though I've been in contact with the language my whole life, and I don't have a beta reader nor will I have one, at least for this story.**_

 _ **There were also 2 ideas I had in mind, this story and one of Shirou Emiya in the world of fairy tail, but the little amount of Ulquiorra fics made me write this one, so I ask of you, write some Ulquiorra fanfic that has the real Ulquiorra in it, heartless and wanting to learn what a heart is.**_


	4. Update

So, I feel like I need to tell you this.

Right now I'm not working on any of the stories, seeing as I've been prioritizing drawing and a certain project I'm working on right now, I hope you can understand why I haven't updated.

If you're interested in what I've been up to check out my Patr eon, right now everything is public, seeing as I have no supporters hehe.

Patr eoncom/AimaZero

just delete the space and add the dot in the link and you're set.

Anyway, I'm not dropping any of the stories, I'm just focused on that for now.

See you soon.


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